Pleural effusion

Alternative names:

exudative pleural effusion; fluid in the chest; transudative pleural effusion

Definition:

An accumulation of fluid between the layers of the membrane lining the lung and the chest cavity.

Causes, incidence, and risk factors:

Pleural fluid is normally formed in small amounts to lubricate the surfaces of the pleura, the thin membrane that surrounds the lungs. A pleural effusion is an abnormal collection of this fluid. Several different types of effusions can develop. Transudative pleural effusions are usually caused by a disorder in the normal pressure in the lung. Congestive heart failure is the most common type of transudative effusion. Exudative effusions form as a result of a disease process in the lung. Cancer, tuberculosis, drug reactions, lung infections, asbestosis, and sarcoidosis are some of the diseases that can cause exudative pleural effusions. The cause and type of pleural effusion can usually be determined by taking a sample of the fluid by thoracentesis (removing fluid through a needle inserted between the ribs into the chest cavity, using a local anesthetic).